Current methods and systems for acquiring and representing sound environments use models based on acquisition means that are physically impracticable, in particular as far as the electro-acoustic and/or structural characteristics of these acquisition means are concerned.
The acquisition means comprise, for example, a set of measuring elements or elementary sensors arranged in specific spatial locations and having intrinsic electro-acoustic acquisition characteristics.
The current systems are limited by the structural characteristics of the acquisition means, such as the physical arrangement and electro-acoustic characteristics of the elementary sensors, and issue degraded representations of the sound environment to be acquired.
The systems subsumed under the term “Ambisonic”, for example, only consider the directions of the source of sounds relative to the centre of the acquisition means comprising a plurality of elementary sensors, which results in the acquisition means being equivalent to a point microphone.
However, the impossibility of positioning all of the elementary sensors at a single point limits the efficiency of these systems.
Furthermore, these systems represent the sound environment by modelling virtual sources, the angular distribution of which around the centre theoretically allows a sound environment of this type to be obtained.
However, the unavailability of elementary sensors having high directivity characteristics limits these systems to a level of representation precision that is commonly known as “order one”, on a mathematical basis known as the basis of spherical harmonics.
In other systems, such as that employing the method and the acquisition device disclosed in patent application No. WO-01-58209, the acquisition is based on the measurement, in a plane, of information that is representative of the sound environment to be acquired.
However, these systems use models based on optimal elementary sensors that are necessarily arranged on a circle and cause significant amplification of the background noise of the sensors.
These systems therefore require sensors of which the intrinsic background noise is extremely low, and are thus impracticable.
Furthermore, in these systems, the sound environment is only described by a bi-dimensional model, which entails a significant and reductive approximation of the real sound characteristics.
It would therefore seem that the representations of sound environments made by the current systems are incomplete and degraded, and that there is no system that allows a faithful representation to be obtained.